Diagnostic Aids

Using scan tool, read MISFIRE CUR # display for each cylinder. This will help locate and isolate which cylinder is affected by misfiring. Check secondary ignition wires. Check for damaged or faulty ignition coils. Substitute a known-good ignition coil. Check system grounds. Check air induction system, fuel pressure, injectors, and EGR valve. Excessive engine vibration could cause DTC to set. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.